Indigo (4)
'indigo' is the definition.
(anil is another word for indigo)
This is the entire clue.
(Other definitions for anil that I've seen before include "Shrub yielding indigo" , "Species of blue" , "Source of dye" , "A blue dye" , "Indian man" .)
(Other definitions for mood that I've seen before include "State of mind, humour" , "Emotional state" , "Temporary state of mind" , "melancholy" , "Doom (anag)" .)